I often use the analogy of a car crash, because a lot of things can go wrong but you get the same result. Statistically, we are only able to determine the cause of a stranding in about 50 percent of all cases worldwide. In some cases it is obvious, like a ship strike leaving an animal in poor condition. In the northeastern United States pneumonia is a common cause of stranding. We see other diseases and trauma, such as shark attack on whales or dolphins or attacks by members of the same species. Poisonous "red tides" will also affect marine mammals. Some strandings have been speculated to be related to anomalies in the magnetic field.